The invention relates to a keyboard housing for a keypad of a push-button keyboard.
From European Patent 0304847 B1 there is known a depressible key for a key array of a keyboard with a housing disposed on a base plate and with an elongate key body which, in its longitudinal direction, is disposed parallel to the base plate and is connected to a plunger, which is guided axially in a housing shaft and to which a swiveling crank arm is fastened. This swiveling crank arm is provided with two crank-arm rods running parallel to the longitudinal direction of the key body and held at a fixed distance from one another by a connecting element, the first being mounted in bearing elements constructed as snap-in elements on the key body and the second crank-arm rod comprising two rod stubs, which are mounted in two lateral receiving elements, each constructed as horizontal parallel slideways.
The swiveling crank arm is provided in order to transfer, during actuation of the depressible key at one end of the key body, part of the actuating force to the other end of the key body, thus preventing the tilting of the key body that would lead to jamming of the plunger connected to the key body in its guide, whereby the function of the depressible key would ultimately be compromised. For the purpose of easier assembly of the depressible key equipped with the elongate key body, there is provided according to European Patent 0304847 B1, on the base plate, at least one downslide which forces the second crank-arm rod out of its engaged position in transverse direction of the key body and feeds it to the receiving elements during introduction of the plunger into the housing shaft. By virtue of this known feature the depressible key can indeed by assembled by a single one-dimensional movement, which can even be accomplished with a special machine. Final assembly, however, is possible only if the swiveling crank arm together with its first crank-arm rod has already been engaged beforehand with the key body in the snap-in apertures provided for the purpose, and thus has been preassembled. Thus combined and simultaneous complete assembly of the multiwide key together with the other keys provided for the keyboard is not possible.
Because of the large number of modern keyboards now being made, however, the greatest possible degree of automation is desired for their production. For example, it is now common practice to make all keys of a keyboard by one-shot injection molding and, by means of a manipulator, to introduce them directly from the injection-molding machine into the keyboard housing in the fitting operation. However, the multi-wide keys with swiveling crank arm of the type described in European Patent 0304847 B1, for example, are not included in this process. Because of the complicated assembly of such multi-wide keys with parallel guide crank arm, the operation of fitting the keyboard housing therewith is usually performed entirely by hand or, after the swiveling crank arm has been manually mounted beforehand on the depressible key, is accomplished by means of a special assembly tool in a separate subsequent assembly process.
The object of the invention is to provide measures which make it possible to include even the key bodies of the multi-wide keys in the injection-molding mold of the depressible keys of the keyboard and, by means of the manipulator, to introduce all key bodies of a keyboard array, including the multi-wide bodies, directly from the injection-molding machine into the keyboard housing for the fitting operation.
This and other objects are attained in accordance with one aspect of the present invention directed to a keyboard housing assembly for a key array of a depressible-key keyboard, comprising a keyboard housing, and a swiveling crank-arm. The keyboard housing is adapted to accommodate at least one depressible multiwide key with a key body elongated in a longitudinal direction and having a first plunger adapted to be guided axially in a shaft of the housing against action of a spring. The multiwide key is adapted to be fastened, in a region of both of its longitudinal ends, to the swiveling crank-arm. The swiveling crank-arm has first and second crank-arm rods running parallel to the longitudinal direction and held at a fixed distance from one another by connecting elements, the first crank-arm rod being adapted to be mounted in bearing elements constructed as snap-in apertures on the key body, and the second crank-arm rod comprising two rod stubs, which are mounted in two lateral receiving elements of the keyboard housing. The swiveling crank-arm is received in the keyboard housing so that its rest position prior to installation of the multiwide key corresponds to that position at which it is located when mounted in the bearing elements and with the multi-wide key body being depressed.
The parallel guide for the multi-wide key is configured in such a way in the keyboard housing according to the invention that the swiveling crank are can be precisely inserted therein in an extremely simple manner.
This parallel guide is advantageously constructed such that the swiveling crank-arm is limited immovably in the longitudinal direction at both ends, and by means of the support ribs is so positioned in the vertical direction that its position corresponds to that of the depressed multi-wide key. If the complete set of depressible keys of a key array is now inserted into the keyboard housing and pressed as far as the end stop, the swiveling crank-arm, precisely introduced beforehand into the keyboard housing, latches into the bearing elements of the multi-wide key provided for the purpose and constructed as snap-in apertures, thus becoming functional.
It is sufficient to provide on the keyboard housing two support ribs, which are disposed at such positions in the upper region of the keyboard housing that the swiveling crank arm together with its two axial end regions naturally rests on them. These two support ribs can be so disposed in the upper region of the keyboard housing that the two connecting elements of the swiveling crank arm naturally rest on them at points close to the first crank-arm rod.
The two lateral receiving elements constructed respectively as horizontal parallel slideways for the two rod stubs of the swiveling crank arm are advantageously provided with a lower horizontal slideway face and an upper horizontal slideway face respectively, which are spaced apart from one another by a distance corresponding to the thickness of the swiveling crank arm. The two receiving elements each contain an L-shaped aperture, so that the respective rod stub of the swiveling crank arm can be introduced between the two slideway faces and, in an action simultaneously coordinated therewith, the connecting element in question of the swiveling crank arm can be introduced in an oblique orientation. The outer lateral edges of these two L-shaped apertures are so disposed that the distance between them corresponds to the length of the swiveling crank arm in longitudinal direction, or in other words to the spacing between the outsides of the connecting elements of the swiveling crank arm. By these features it is ensured on the one hand that the two rod stubs of the swiveling crank arm can be displaced slidingly during insertion into the two receiving elements comprising the parallel guide, and on the other hand that the swiveling crank arm is securely limited against longitudinal displacement.
The features and improvements indicated in the foregoing, which relate to mounting of the multi-wide key body together with its swiveling crank arm on the keyboard housing, are preferably provided in the region of its two ends and, in fact, in mirror-image manner relative to its central plane oriented perpendicular to the longitudinal direction. By this measure and, in a further expedient version, also by the measure that auxiliary plungers guided axially in associated housing shafts are disposed on the key body on both sides of and parallel to the centrally disposed plunger, tilting of the key body is reliably prevented.